I have been taking Propecia for two months for aggressive male pattern baldness at age 23 (Norwood 3 approaching). It has restricted my hair loss. I want to continue the medication. I have normal morning erections, but my libido has decreased. I want to be on the medication for at least one year. This is a personal choice.
If you are willing to manage the decreased libido to maintain your hair, then by all means continue the drug.